This invention relates to forming piezoelectric material.
Piezoelectric materials can generate a voltage differential when subjected to mechanical stress. Alternatively, applying a voltage across a piezoelectric material can cause converse piezoelectricity, that is, the piezoelectric material mechanically deforms when a voltage is applied. Converse piezoelectricity can cause bending forces in the piezoelectric material that are extremely high. Both of these properties, generating electricity and converse piezoelectricity, are harnessed for use in electrical and mechanical devices, such as transducers, e.g., actuators and sensors. Multiple transducers, including a combination of actuators and sensors, can be combined together in a microelectromechanical system (MEMS).
Piezoelectric materials, such as lead zirconium titanate, can also be used to form ferroelectric RAM (FRAM). The piezoelectric material for either actuators or FRAMs can be obtained from a sol gel, ceramic green sheets, metal-organic chemical vapor deposition (MOCVD) formed layers or pre-fired blocks of piezoelectric material. However, each method can form piezoelectric materials of different quality and composition. For example, a sol gel formation technique may require many individual thin layers to form a thick piezoelectric material. Also sol gel formation can leave bonding agents in the final material. MOCVD typically forms thin layers of piezoelectric material and can have very low deposition rates.